1. Field of the Invention
The present invention relates to a phase locked loop (PLL), and more particularly to a phase locked loop for synchronizing decoding clocks with encoding clocks in a Moving Picture Experts Group (MPEG) system.
2. Description of the Prior Art
System coding in MPEG systems is carried out using transport streams or program streams. Transport streams are applied to an environment involving errors whereas program streams are applied to an environment relatively free of errors. In the case of the present invention, transport streams are used.
Programs with one or more independent time bases are coupled to a string of bits which is called "a transport stream". In this case, packetized elementary streams (PES's) each consisting of a string of elementary bits form programs sharing the same time base, respectively. Such transport stream packets have a length of 188 bytes and are variable in bit rate. The bit rate of transport stream packets is determined by the position and value of the field of a program clock reference (PCR). The synchronization among multiple elementary bit strings is enabled by the PCR.